Method for assembling a polishing head and apparatus for detecting air leakage in the polishing head while assembling the same

ABSTRACT

Disclosed are a method for assembling a polishing while inspecting for air leakage in the polishing head and an apparatus for performing the same. By the present invention, a polishing head may be tested for air leakage at each assembly step thereof, so that the polishing head may be assembled free of air leakage, thereby reducing testing time of the polishing head, and failure of the polishing head due to air leakage may be prevented. The apparatus includes a housing supporting the polishing head and having coupling lines coupled with ends of tubes provided in the assembled polishing head, or the polishing head being assembled. A pneumatic pressure regulating section selectively supplies positive pressure or vacuum to the tubes through the coupling lines. A sensor section detects the pressure and level of vacuum in the tubes. A determining section determines if there is air leakage in the polishing head.

CROSS REFERENCE TO RELATED APPLICATION(S)

This is a divisional application based on application Ser. No.10/259,639, filed Sep. 30, 2002, now U.S. Pat. No. 6,754,942 B2, theentire contents of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a method for assembling a polishinghead and an apparatus for detecting air leakage in the polishing headwhile assembling the same. More particularly, the present inventionrelates to a method for assembling a polishing head while inspectingeach tube of the polishing head for air leakage and an apparatussuitable for performing the method.

2. Description of the Related Art

Semiconductor technology is making great strides as information mediasuch as computers are becoming more widely used. In a functional aspect,a semiconductor device is required to be operated at a high speed with alarge storage capacity. Accordingly, semiconductor technology isdeveloped to improve the degree of integration, the reliability, and theresponse speed of semiconductor devices. Therefore, micro-processingtechniques are governed by strict requirements in order to improve thedegree of integration of semiconductor devices.

Among the micro-processing techniques for improving the degree ofintegration of semiconductor devices is a planarization technique. Inthe semiconductor manufacturing industry, chemical mechanical polishing(CMP), in which a wafer is directly polished, is primarily used as aplanarization technique.

In order to evenly planarize a wafer using the CMP process, it isimportant that uniform pressure is applied to each part of the waferduring the CMP process. Accordingly, it is important to provide a properpolishing head, which grips the wafer (holds the wafer by applyingsuction to the wafer) thereby applying pressure to the wafer during theCMP process.

Specifically, an inner portion of the polishing head has a plurality oftubes used for air passage. A pneumatic pressure or a vacuum is suppliedthrough the tubes. At this time, the wafer below the polishing head ispushed towards a polishing pad by the pneumatic pressure supplied to thepolishing head, so that a contact-pressure between the wafer and thepolishing pad increases. In addition, the wafer is gripped by suction ata lower portion of the polishing head by the vacuum supplied to thepolishing head. However, if there is any air leakage in the tubes of thepolishing head, the predetermined pneumatic pressure or thepredetermined vacuum cannot be normally supplied to the polishing head.In such a case of air leakage in the tubes, the wafer is unevenlypolished due to non-uniform pressure, or the wafer falls from thepolishing head due to insufficient suction.

The prior art discloses a polishing device including a polishing headhaving an air line for controlling the operation of the polishing headand an air control system for controlling the polishing head. The aircontrol system inspects for air leakage in the air line of the polishinghead installed in the polishing device. In addition, the prior artdiscloses a polishing head capable of checking for the existence of awafer by detecting a pressure variation.

The polishing head has to be periodically disassembled for cleaning orexchanging parts thereof. After being re-assembled, the polishing headis installed in the polishing device. If the polishing head isincorrectly assembled, the pneumatic pressure or the vacuum supplied tothe polishing head leaks therefrom, so that the polishing head is unableto grip the wafer or the wafer does not receive a precise pressure.Therefore, after assembling the polishing head, testing the polishinghead for the existence of air leakage is required. Only if the polishinghead does not generate any air leakage can it be used in the CMPprocess.

The test method is as follows. Firstly, the assembled polishing head isinstalled in the polishing device. Then, the CMP process, in which awafer is gripped by the polishing head, is carried out using a dummywafer. Thereafter, a surface of the polished dummy wafer is inspected todetect scratches and particles formed thereon, thereby determiningwhether or not the dummy wafer is normally polished. Upon completion ofthe test, if the dummy wafer is normally polished, a wafer formanufacturing a semiconductor device is introduced into the polishingdevice equipped with the polishing head, and the CMP process is carriedout with respect to the wafer.

If the dummy wafer is abnormally polished, a user separates thepolishing head from the polishing device in order to disassemble andre-assemble the polishing head. Then, after re-assembling the polishinghead, the leakage test must again be carried out using a dummy wafer totest the polishing head. The leakage test takes about 6 hours. Sinceabout 10% of assembled polishing heads have some air leakage, it isnecessary to re-assemble the polishing heads about 10% of the time,resulting in a marked reduction in production from the polishing device.Accordingly, productivity of the semiconductor device manufacturingequipment is also lowered.

SUMMARY OF THE INVENTION

In order to solve the problems mentioned above, it is a first feature ofan embodiment of the present invention to provide a method forassembling a polishing head while inspecting the polishing head for airleakage.

A second feature of an embodiment of the present invention is to providean apparatus for inspecting a polishing head for air leakage duringassembly of the polishing head.

To provide the first feature of an embodiment of the present invention,the method for assembling a polishing head while inspecting for airleakage in the polishing head includes assembling an inner tube to ahousing and a base, supplying a first pressure through a first pressureline to a first tube connected to the inner tube and inspecting for airleakage by determining if there is any variation in the first pressurein the first tube connected to the inner tube, assembling a membrane tothe base once the inner tube is assembled, supplying a second pressurethrough a second pressure line to a second tube connected to themembrane and inspecting for air leakage by determining if there is anyvariation in the second pressure in the second tube connected to themembrane, supplying a first level of vacuum through a first vacuum lineto the second tube connected to the membrane and inspecting for airleakage by determining if there is any variation in the level of vacuumin the second tube connected to the membrane, assembling a retainer ringto the base once the membrane is assembled, thereby completing anassembling of the polishing head, supplying a third pressure through athird pressure line to a third tube connected to the retainer ring andinspecting for air leakage by determining if there is any variation inthe third pressure in the third tube connected to the retainer ring, andsupplying a second level of vacuum through a second vacuum line to thethird tube connected to the retainer ring and inspecting for air leakageby determining if there is any variation in the second level of vacuumin the third tube connected to the retainer ring.

Preferably, inspecting for air leakage is carried out by supplying apredetermined pressure or level of vacuum to a predetermined tube of thepolishing head to be inspected while tubes that are not subject toinspection are closed, closing the predetermined pressure or vacuumline, through which the predetermined pressure or level of vacuum issupplied to the predetermined tube when the pressure or level of vacuumin the predetermined tube reaches the predetermined pressure or level ofvacuum, determining if there is any variation in the pressure or levelof vacuum in the predetermined tube after a predetermined period of timeafter closing the predetermined pressure or vacuum line, determiningwhether air leakage occurs by measuring any variation in the pressure orlevel of vacuum in the predetermined tube and comparing the variation inthe pressure or level of vacuum with a predetermined pressure or levelof vacuum. Also, the pressure in the predetermined tube is preferablyvented after inspecting for air leakage.

To provide the second feature of an embodiment of the present invention,there is provided an apparatus for inspecting a polishing head for airleakage. The apparatus includes a housing operatively associated with anupper surface of the polishing head for supporting the polishing head,the housing having first, second and third coupling lines, the polishinghead having first, second and third tubes, wherein each coupling line ofthe housing is independently communicated with a corresponding tube ofthe polishing head, a pneumatic pressure regulating section forselectively supplying a positive pressure or a vacuum to each of thetubes of the polishing head through the coupling lines of the housing, asensor section for detecting, measuring and generating data relating toa level of positive pressure or vacuum in each of the tubes of thepolishing head, and a determining section for receiving data relating toa level of positive pressure or vacuum in each of the tubes of thepolishing head from the sensor section to ascertain whether air leakageexists in the polishing head by determining if the level of positivepressure or vacuum in each of the tubes of the polishing head ismaintained over a predetermined period of time.

Preferably, the first, second and third tubes provided in the polishinghead that are respectively communicated with the first, second and thirdcoupling lines of the housing, are first, second and third air passages,respectively, and are respectively communicated with an inner tube, amembrane and a retainer ring of the polishing head. Also, the first airpassage communicated with the inner tube preferably receives onlypositive pressure from the pneumatic pressure regulating section.

The pneumatic pressure regulating section preferably includes a mainpressure regulating device for supplying positive pressure into thefirst, second and third tubes of the polishing head, a main vacuumregulating device for supplying vacuum into the second and third tubesof the polishing head, a first connection line connected to the mainpressure regulating device for transferring positive pressure suppliedfrom the main pressure regulating device, first, second and thirdpressure lines branched from the first connection line and connectedrespectively to the first, second and third coupling lines of thehousing, each of the first, second and third pressure lines having afirst valve for selectively opening and closing the first, second andthird pressure lines, a second connection line connected to the mainvacuum regulating device for transferring vacuum supplied from the mainvacuum regulating device, first and second vacuum lines branched fromthe second connection line and connected respectively to the second andthird coupling lines of the housing, each of the first and second vacuumlines having a second valve for selectively opening and closing thefirst and second vacuum lines, and a third connection line connected tothe second coupling line of the housing, and connecting the secondpressure line to the first vacuum line so that the second pressure lineand the first vacuum line are connected to the second coupling line ofthe housing, and a fourth connection line connected to the thirdcoupling line of the housing, and connecting the third pressure line tothe second vacuum line so that the third pressure line and the secondvacuum line are connected to the third coupling line of the housing.

Preferably, the first pressure line is directly connected to the firstcoupling line of the housing communicated with the inner tube of thehousing.

The apparatus may further include a venting valve connected to each ofthe first valves and the first, second and third pressure lines to allowor prevent discharge of pressure from each of the tubes of the polishinghead to an exterior.

Preferably, the sensor section includes first sensors provided on eachof the first valves and the first, second and third pressure linesconnected to the first, second and third coupling lines of the housingto detect pressure in the first, second and third tubes of the polishinghead, and second sensors provided on each of the second valves and thefirst and second vacuum lines connected to the second and third couplinglines of the housing to detect a level of vacuum in the second and thirdtubes of the polishing head. Preferably, a timer is attached to each ofthe sensors of the sensor section for notifying of a lapse of time.

The apparatus may further include first control sections connected tothe first sensors and the first valves for driving the first valvesbased on the data obtained from the first sensors in order toindividually control pressure supplied to the first, second and thirdtubes of the polishing head, and second control sections connected tothe second sensors and the second valves for driving the second valvesbased on the data obtained from the second sensors in order toindividually control the vacuum supplied into the second and third tubesof the polishing head.

The apparatus may further include a driving section having a rail andcoupled to a predetermined side portion of the housing for moving thehousing and the polishing head supported by the housing in upward anddownward directions along the rail, a motor connected to the housing fordriving the housing along the rail, and a measuring section formeasuring a driving distance of the housing.

There is preferably a seat sensor provided opposite to a bottom of thepolishing head supported by the housing for detecting the pressure ateach part of the bottom of the polishing head by making contact with thebottom of the polishing head, and a display section for displaying thepressure detected from each part of the seat sensor.

By using the assembling method and apparatus for a polishing head of thepresent invention, air leakage may be detected during assembly of thepolishing head, unlike in the prior art, in which testing for airleakage is not performed until the polishing head is fully assembled andinstalled. If air leakage is detected during the process of assemblingthe polishing head in the present invention, the assembly stepimmediately prior to the detection of air leakage is repeated, and theleakage test is repeated, so that the polishing head may be assembledwithout any air leakage. Accordingly, by using the present invention, alengthy test of the completely assembled and installed polishing head isunnecessary. In the prior art, if the polishing head is abnormallyassembled and a leak is detected, all parts of the polishing head mustbe disassembled and re-assembled in order to stop the leak, a processthat is eliminated by the present invention. Furthermore, when using thepresent invention, after assembling the polishing head, the polishinghead may be installed in a polishing device and immediately used topolish a wafer, without having to be tested on a dummy wafer first,thereby improving the productivity of the semiconductor devicemanufacturing equipment.

BRIEF DESCRIPTION OF THE DRAWINGS

The above features and other advantages of the present invention willbecome more apparent by describing in detail preferred embodimentsthereof with reference to the attached drawings in which:

FIG. 1 depicts a sectional view of a polishing head equipped in apolishing device;

FIGS. 2 and 3 depict front and side views of an apparatus for inspectinga polishing head according to one embodiment of the present invention;

FIG. 4 depicts a view of a pneumatic pressure regulating section used inthe inspecting apparatus according to one embodiment of the presentinvention;

FIGS. 5A and 5B depict a flow chart illustrating a method for inspectingeach tube of the polishing head into which the pneumatic pressure issupplied for air leakage, during assembly of the polishing head andafter the polishing head has been assembled; and

FIG. 6 depicts a flow chart illustrating a step of determining apressure applied to a wafer by the polishing head.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Korean Patent Application Number 2001-60574, filed on Sep. 28, 2001, andentitled: “Method for Assembling a Polishing Head and Apparatus forInspecting an Air Leakage in the Polishing Head While Assembling theSame,” is incorporated by reference herein in its entirety.

Hereinafter, preferred embodiments of the present invention will bedescribed in detail with reference to the accompanying drawings.

FIG. 1 depicts a sectional view of a polishing head equipped in apolishing device.

Referring to FIG. 1, a polishing head 10 includes a body 20 capable ofrotating and moving up and down. The body 20 includes a housing 12 and abase 14 for supporting the housing 12. The housing 12 has upper andlower surfaces having a circular shape, and a first tube 16 a passingthrough a center of the housing 12 from the upper surface to the lowersurface of the housing 12. In addition, second and third tubes 16 b and16 c passing through the housing 12 from the upper surface to the lowersurface of the housing 12 are spaced apart radially outward by apredetermined distance from the first tube 16 a. The first to thirdtubes 16 a, 16 b and 16 c act as air passages 16.

A retainer ring 22 is provided at a lower peripheral portion of the base14 of the body 20 to prevent a wafer from drifting laterally. Inaddition, a perforated plate 26 is installed in the retainer ring 22 ata lower portion of the body 20 to distribute pressurized air to besupplied. A membrane 28 having a predetermined elasticity is provided tofully cover a lower surface of the perforated plate 26. A rear surfaceof the wafer being polished makes contact with a lower surface of themembrane 28. Specifically, the membrane 28 expands and shrinks due tothe pressurized air or vacuum supplied through the first tube 16 a,which applies pressure or suction to the wafer.

The second tube 16 b is connected to the inner tube 30, which iscontinuously formed at a periphery of the perforated plate 26. Pneumaticpressure supplied through the second tube 16 b causes the inner tube 30to expand. Accordingly, an upper surface of the periphery of theperforated plate 26 is pushed by the pressure, which is created by theexpansion of the second tube 16 b, so that the pressure is applied to apredetermined portion of the wafer to be polished.

The third tube 16 c is communicated with a first chamber 32 definedbetween the housing 12 and the base 14. The pressurized air or vacuum issupplied into the first chamber 32 through third tube 16 c, so thatpressure or suction is applied to the retainer ring 22 provided at alower portion of the base 14.

FIGS. 2 and 3 illustrate front and side views of an apparatus forinspecting the polishing head according to an embodiment of the presentinvention.

Referring to FIGS. 1, 2 and 3, the apparatus includes a housing 42operatively associated with an upper surface of the polishing head 10 tosupport the polishing head 10. The housing 42 has first, second andthird coupling lines 40 b, 40 a and 40 c that are separately coupled toends of first, second and third tubes 16 b, 16 a and 16 c provided inboth the assembled polishing head and the polishing head beingassembled. The coupling lines 40 a, 40 b and 40 c of the housing 42respectively supply the positive pressure or level of vacuum to thetubes 16 a, 16 b and 16 c of the polishing head 10. In addition, thecoupling lines 40 a, 40 b and 40 c of the housing 42 are respectivelycoupled to the tubes 16 a, 16 b and 16 c of the polishing head 10 by aclamp (not shown) so as to prevent a leakage therebetween.

In detail, the tubes 16 a, 16 b and 16 c provided in the polishing head10 act as air passages respectively communicated with the membrane 28,the inner tube 30 and the retainer 22 included in the polishing head 10.The membrane 28, the inner tube 30 and the retainer 22 included in thepolishing head 10 receive the pneumatic pressure through the tubes 16 a,16 b and 16 c respectively communicated therewith while the polishingprocess is carried out, thereby gripping (holding the wafer by suction)or uniformly polishing the wafer. When the polishing process is carriedout, only pressure is supplied to the tube communicated with the innertube 30. Accordingly, the inner tube 30 is expanded due to the pressureand pushes the predetermined portion of the wafer positioned below thepolishing head 10, so that the wafer is uniformly polished. On thecontrary, pressure or vacuum is selectively supplied to the retainerring 22, which prevents the wafer from drifting in a lateral direction,and the membrane 28, which grips the wafer or applies pressure to thewafer.

The coupling lines 40 a, 40 b and 40 c provided in the housing 42 may berespectively coupled to the tubes 16 a, 16 b and 16 c communicated withthe membrane 28, the inner tube 30 and the retainer ring 22 in a statethat the polishing head 10 is completely assembled. In a specific case,at least one of the tubes 16 a, 16 b and 16 c communicated with themembrane 28, the inner tube 30 and the retainer ring 22 is selected tobe coupled with the respective coupling lines 40 a, 40 b and 40 c whilethe polishing head is being assembled. By coupling the tubes of thepolishing head 10 to the coupling lines of the housing 42, the uppersurface of the polishing head may be supported by the housing 42.

A driving section 47 has a rail 44 and is coupled to a predeterminedside portion of the housing 42 for moving the housing 42 and thepolishing head 10 supported by the housing 42 in upward and downwarddirections along the rail. In addition, a motor 46 is connected to thehousing 42 for supplying a driving force for driving the housing 42 inthe upward or downward direction along the rail 44. A measuring section48 is provided to measure the driving distance of the housing 42 movingalong the rail 44. When the housing 42 is driven by the driving section47, the polishing head 10 supported by the housing 42 is simultaneouslydriven in the upward or downward direction. Therefore, when the couplinglines 40 a, 40 b and 40 c provided in the housing 42 are coupled withtubes 16 a, 16 b and 16 c of the polishing head 10, the user may placethe housing 42 in a proper working position. In addition, it is alsopossible to test for air leakage in the polishing head 10 by setting adistance between the polishing head 10 coupled to the housing 42 and apredetermined portion opposite to the polishing head 10 to be identicalto a distance between the polishing pad and the polishing head 10 in thepolishing process.

A pneumatic pressure regulator 50 (refer to FIG. 4) is provided tosupply the pressure or vacuum into tubes 16 a, 16 b and 16 c of thepolishing head 10 coupled with the housing 42. The pneumatic pressureregulator 50 individually supplies the required pressure to the tubes 16a, 16 b and 16 c of the polishing head 10 through the coupling lines 40a, 40 b and 40 c and the vacuum to the tubes 16 a and 16 c of thepolishing head 10 through the coupling lines 40 a and 40 c.

FIG. 4 shows an example of a pneumatic pressure regulating section usedin the inspecting apparatus when assembling the polishing head accordingto an embodiment of the present invention.

Referring to FIGS. 2 and 4, a main pressure regulator 52 is provided tosupply the pressure into each of the tubes 16 a, 16 b and 16 c of thepolishing head 10. In addition, a main vacuum regulator 54 is providedto supply the vacuum into the tubes 16 a and 16 c of the polishing head10.

A first connection line 56 is connected to the main pressure regulator52 in order to transfer the positive pressure supplied from the mainpressure regulator 52. In addition, a plurality of pressure lines 56 a,56 b and 56 c are branched from the first connection line 56 towards thecoupling lines 40 a, 40 b and 40 c of the housing 42. Accordingly, thepositive pressure supplied from the main pressure regulator 52 istransferred into the pressure lines 56 a, 56 b and 56 c through thefirst connection line 56.

First valves 58 a, 58 b and 58 c are provided on the pressure lines 56a, 56 b and 56 c. Each of the first valves 58 a, 58 b and 58 c is ableto control the opening and closing of the pressure lines 56 a, 56 b and56 c. Accordingly, the positive pressure and vacuum may be selectivelysupplied to the coupling lines 40 a, 40 b and 40 c of the housing.

Particularly, the first connection line 56 is preferably branched intothe coupling lines 40 a, 40 b and 40 c of the housing 42 communicatedwith the membrane 28, the inner tube 30 and the retainer ring 22 of thepolishing head 10. Therefore, the three pressure lines 56 a, 56 b and 56c are provided on the first connection line 56. In addition, each of thefirst valves 58 a, 58 b and 58 c is provided on each of the pressurelines 56 a, 56 b and 56 c. At this time, each of the three first valves58 a, 58 b and 58 c may be independently controlled, making it possibleto shut off the positive pressure or selectively supply thepredetermined positive pressure independently to each of the tubes 16 a,16 b and 16 c of the polishing head 10 respectively connected to themembrane 28, the inner tube 30 and the retainer ring 22. Venting valves60 a, 60 b and 60 c are connected in a row to the first valves 58 a, 58b and 58 c provided on the pressure lines 56 a, 56 b and 56 c. Theventing valves 60 a, 60 b and 60 c allow the positive pressure suppliedinto each of the tubes 16 a, 16 b and 16 c of the polishing head 10through the pressure lines 56 a, 56 b and 56 c to be discharged to theexterior. That is, by opening the venting valves 60 a, 60 b and 60 cwhile shutting off the first valves 58 a, 58 b and 58 c, the pressure ineach of the tubes 16 a, 16 b and 16 c of the polishing head 10 may bedischarged to the exterior through the venting valves 60 a, 60 b and 60c. The venting valves 60 a, 60 b and 60 c are provided in order todischarge the pressure from the tubes 16 a, 16 b and 16 c when thepressure is no longer supplied into the tubes 16 a, 16 b and 16 c. Whilethe pressure is being supplied into the tubes 16 a, 16 b and 16 c, theventing valves 60 a, 60 b and 60 c are closed.

A second connection line 64 is connected to the main vacuum regulator 54in order to allow transfer of the vacuum supplied by the main vacuumregulator 54. Also, a plurality of vacuum lines 64 a and 64 c arebranched from the second connection line 64 and respectively coupled tocoupling lines 40 a and 40 c of the housing 42. Accordingly, vacuumsupplied from the main vacuum regulator 54 may be transferred to vacuumlines 64 a and 64 c through the second connection line 64.

Second valves 66 a and 66 c are provided on the vacuum lines 64 a and 64c, respectively, to allow the vacuum lines 64 a and 64 c to be opened orclosed. Therefore, the vacuum supplied through the vacuum lines 64 a and64 c may be selectively supplied to the coupling lines 40 a and 40 c ofthe housing 42.

The vacuum lines 64 a and 64 c preferably are not branched into thecoupling line 40 b of the housing communicated with the inner tube 30 ofthe polishing head 10. The reason for this is that only pressure issupplied into the inner tube 30 of the polishing head 10 when thepolishing process is carried out, and vacuum lines 64 a and 64 c areused to supply vacuum.

Particularly, the vacuum lines 64 a and 64 c are branched into thecoupling lines 40 a and 40 c of the housing 42, which are communicatedwith the membrane 28 and the retainer ring 22 of the polishing head 10.Because the two second valves 66 a and 66 c may be individuallycontrolled, it is possible to selectively supply the vacuum to the tubes16 a and 16 c of the polishing head 10, which are connected to themembrane 28 and the retainer ring 22.

In addition, a third connection line 68 a allows pressure line 56 a andvacuum line 64 a to be connected together in a row, and to be connectedto coupling line 40 a of the housing 42 communicated with the membrane28. A fourth connection line 68 c allows pressure line 56 c and vacuumline 64 c to be connected together in a row, and to be connected tocoupling line 40 c of the housing 42 communicated with the retainer ring22. The third and fourth connection lines are necessary because bothvacuum and pressure are selectively supplied to the coupling lines 40 aand 40 c.

Since the coupling line communicated with the inner tube 30 is notconnected to the vacuum lines 64 a and 64 c, another connection line isnot required thereto. Therefore, the pressure line 56 b provided tosupply the pressure to the inner tube 30 is directly connected to thecoupling line 40 b of the housing 42 communicated with the inner tube30.

Accordingly, the pneumatic pressure regulator 50 shown in FIG. 4 iscapable of supplying the predetermined positive pressure into each ofthe tubes 16 a, 16 b and 16 c of the polishing head 10, and thepredetermined level of vacuum to both the tubes 16 a and 16 c of thepolishing head 10.

Hereinafter, the apparatus for inspecting the polishing head for leakagewhile assembling the polishing head will be further described withrespect to FIGS. 2, 3 and 4.

A sensor section 73 detects the pressure or level of vacuum in each ofthe tubes 16 a, 16 b and 16 c of the polishing head 10. Sensors 70 a, 70b, 70 c, included in the sensor section 73 are respectively provided onthe pressure lines 56 a, 56 b and 56 c, and sensors 72 a and 72 cincluded in the sensor section 73 are respectively provided on thepressure lines 64 a, and 64 c for supplying the pressure or level ofvacuum into each of the tubes 16 a, 16 b and 16 c. In addition, timers74 a, 74 b, 74 c, 76 a and 76 c are provided in each sensor to notifythe user of a lapse of time.

The positions of each sensor 70 a, 70 b, 70 c, 72 a and 72 c in thepneumatic pressure regulator 50 will now be described. The sensors 70 a,70 b and 70 c are respectively provided in the pressure lines 56 a, 56 band 56 c supplying the pressure into each of the tubes 16 a, 16 b and 16c, and the sensors 72 a and 72 c are respectively provided in the vacuumlines 64 a and 64 c supplying the level of vacuum into each of the tubes16 a and 16 c. At this time, sensors 70 a, 70 b, 70 c, 72 a and 72 c arerespectively positioned at rear ends of valves 58 a, 58 b, 58 c, 66 aand 66 c respectively provided on the pressure and vacuum lines 56 a, 56b, 56 c, 64 a and 64 b.

Specifically, first sensors 70 a, 70 b and 70 c are respectivelyprovided in the pressure lines 56 a, 56 b and 56 c which connect thefirst valves 58 a, 58 b and 58 c to coupling lines 40 a, 40 b and 40 cof the housing 42. Accordingly, the first sensors 70 a, 70 b and 70 care able to detect the positive pressure in each of the tubes 16 a, 16 band 16 c, which is varied depending on the operating state of the firstvalves 58 a, 58 b and 58 c. First control sections 78 a, 78 b and 78 care respectively connected to the first sensors 70 a, 70 b and 70 c andthe first valves 58 a, 58 b and 58 c in order to drive the first valves58 a, 58 b and 58 c based on data obtained from the first sensors 70 a,70 b and 70 c. The first control sections 78 a, 78 b and 78 c shut offthe first valves 58 a, 58 b and 58 c when the pressure in each of thetubes 16 a, 16 b and 16 c maintains a predetermined pressure, therebyindividually controlling the positive pressure supplied to each of thetubes 16 a, 16 b and 16 c.

In addition, second sensors 72 a and 72 c for detecting the level ofvacuum are respectively provided in the vacuum lines 64 a and 64 c whichconnect the second valves 66 a and 66 c to coupling lines 40 a and 40 cof the housing 42. Accordingly, the second sensors 72 a and 72 c areable to detect the level of vacuum in the tubes 16 a and 16 c, which isvaried depending on the control state of the second valves 66 a and 66c. At this time, it is possible to provide second control sections 80 aand 80 c connected to the second sensors 72 a and 72 c and the secondvalves 66 a and 66 c to drive the second valves 66 a and 66 c based ondata detected by the sensors 72 a and 72 c. The second control sections80 a and 80 c shut off the second valves 66 a and 66 c when the level ofvacuum in each of the tubes 16 a and 16 c maintains a predeterminedvalue, thereby individually controlling the level of vacuum supplied tothe tubes 16 a and 16 c.

In addition, determining sections 82 a, 82 b and 82 c are provided fordetermining the air leakage in the polishing head 10. The determiningsections 82 a, 82 b and 82 c receive data relating to a level ofpositive pressure or vacuum in each of the tubes 16 a, 16 b and 16 cfrom sensors 70 a, 70 b, 70 c, 72 a and 72 c of the sensor section 73 toascertain whether air leakage exists in the polishing head bydetermining if the positive pressure or the level of vacuum in each ofthe tubes is maintained over a predetermined period of time.

Specifically, in order to inspect each of the tubes 16 a, 16 b and 16 cof the polishing head 10 for air leakage, the predetermined level ofpositive pressure or vacuum is supplied to each of the tubes 16 a, 16 band 16 c. Then, the valves 58 a, 58 b, 58 c, 66 a and 66 c respectivelyconnected to the tubes are closed. At this time, the determiningsections 82 a, 82 b and 82 c continuously receive the data relating to alevel of positive pressure or vacuum and ascertain whether or not thelevel of positive pressure or vacuum in each of the tubes is in a rangeof predetermined values after a predetermined period of time in order todetermine whether air leakage exists in each of the tubes. After closingthe valves 58 a, 58 b, 58 c, 66 a and 66 c, timers 74 a, 74 b, 74 c, 76a and 76 c provided in the sensors 70 a, 70 b, 70 c, 72 a and 72 c areoperated to notify the user of the lapse of time.

A seat sensor 84, for detecting the level of positive pressure in eachpart of the bottom of the polishing head 10, is positioned opposite to abottom of the polishing head 10. The seat sensor 84 is able to detectthe pressure at each part of an upper surface thereof. A display section86 is connected to the seat sensor 84 for displaying the pressure valuedetected from each part of the seat sensor 84.

Accordingly, the contact pressure between the bottom of the polishinghead 10 and the upper surface of the seat sensor 84 may be obtainedafter supplying the pneumatic pressure into the membrane 28, the innertube 30 and the retainer ring 22 of the assembled polishing head 10. Thecontact pressure allows the user to recognize whether or not thepressure is evenly applied to the entire surface of the wafer by thepolishing head 10. At this time, a distance between the polishing head10 and the seat sensor 84 is identical to a distance between thepolishing pad and the polishing head 10 in the polishing process. Inaddition, it is possible to obtain the optimum condition for polishingthe entire surface of the wafer by monitoring the pressure applied tothe seat sensor while controlling the positive pressure applied to eachof the tubes 16 a, 16 b and 16 c.

Hereinafter, a method for assembling the polishing head while inspectingthe polishing head for air leakage by means of the above-mentionedleakage inspecting apparatus will be described, with reference to FIGS.5A and 5B. Also, reference numerals in the following description referto those of FIGS. 1–4.

FIGS. 5A and 5B depict a flow chart illustrating a method for assemblingthe polishing head according to an embodiment of the present invention.

The inner tube 30 is assembled to the housing 12 and the base 14. Aworker manually carries out the assembly work (step S10).

Then, a predetermined positive pressure is supplied to the tube 16 bconnected to the inner tube 30. After that, the pressure line 56 bsupplying the positive pressure to the tube 16 b is shut-off and thepressure in the tube 16 b is measured in order to inspect for airleakage in the inner tube 30 (step S12).

Specifically, an end of the tube 16 b connected to the inner tube 30 iscoupled with the coupling line 40 b of the housing 42 by means of aclamp. Then, the predetermined positive pressure is supplied to theinner tube 30 through the pressure lines 56 a and 56 c connected to themain pressure regulator 52. At this time, the positive pressure suppliedfrom the main pressure regulator 52 is not transferred to the membrane28 and the retainer ring 22. That is, the first valve 58 b provided inthe pressure line 56 b communicated with the inner tube 30 is opened,and the first valves 58 a and 58 c provided in the pressure lines 56 aand 56 c, respectively, are closed, such that the positive pressure issupplied only to the inner tube 30. When the pressure in the inner tube30 reaches the predetermined pressure, the first control section 78 bformed in the pressure line 56 b communicated with the inner tube 30closes the first valve 58 b such that the positive pressure is no longersupplied into the inner tube 30. Then, after the predetermined period oftime, the pressure in the inner tube 30 is measured to detect whether ornot the inner tube 30 maintains the predetermined pressure, therebydetermining whether or not any air leakage exists in the inner tube 30.If the pressure in the inner tube 30 is within a predetermined range, itis determined that air leakage does not exist in the inner tube 30.However, if the pressure in the inner tube 30 is below the predeterminedrange, it is determined that air leakage does exist in the inner tube30.

When air leakage is detected at the inner tube 30 through the aboveinspection (step S14), the inner tube 30 is disassembled (step S15) inorder to be re-assembled (step S10). The leakage inspection test (stepS12) described above is then repeated on the re-assembled inner tube 30.

When the leakage inspection at the inner tube 30 is completed, thepositive pressure supplied to the inner tube 30 is vented by openingventing valve 60 b connected in a row to first valve 58 b provided inpressure line 56 b.

Then, the membrane 28 is assembled to the base 14 once the inner tube 30has been assembled (step S16).

A predetermined positive pressure is supplied into the tube 16 aconnected to the membrane 28. Then, the pressure line 56 a supplying thepositive pressure to the tube 16 a is shut-off, and the pressure in thetube 16 a is measured in order to inspect for air leakage in themembrane 28 (step S18).

The method for inspecting for air leakage in the membrane 28 issubstantially identical to the method for inspecting for air leakage inthe inner tube 30, except that the positive pressure is supplied to thetube 16 a communicated with the membrane 28, instead of the tube 16 bcommunicated with the inner tube 30, so the detailed description thereofwill be omitted. At this time, the predetermined positive pressure issupplied only to the tube connected to the membrane 28, and the tubecommunicated with the inner tube 30 is closed.

If air leakage is detected in the membrane 28 through the aboveinspection (step S20), the membrane 28 is disassembled (step S19) inorder to be re-assembled (step S16). The leakage inspection test (I)(step S18) described above is then repeated on the re-assembled membrane28.

When the leakage inspection in the membrane (I) performed by supplyingthe pressure is completed, the pressure in the membrane 28 is vented tothe exterior by opening venting valve 60 a connected, in a row, to firstvalve 58 a provided in first branch line 56 a.

Then, the vacuum is supplied to the membrane 28 in order to performleakage inspection in the membrane 28 (I I) (step S22).

Specifically, a predetermined level of vacuum is supplied to the tube 16a connected to the membrane 28 through vacuum lines 64 and 64 aconnected to the main vacuum regulator 54. At this time, the secondvalve 66 c in the vacuum line 64 c communicated with the retainer ring22 is closed, so that the vacuum is supplied only to the membrane 28.When the predetermined level of vacuum is reached in the membrane 28,second control section 80 a provided in vacuum line 64 a communicatedwith the membrane 28 closes the second valve 66 a, so that the vacuum isno longer supplied to the membrane 28. Then, after the predeterminedperiod of time, the level of vacuum in the membrane 28 is measured todetect whether or not the membrane 28 maintains the predetermined levelof vacuum, thereby determining whether or not any air leakage exists inthe membrane 28. If the level of vacuum in the membrane 28 is within apredetermined range, it is determined that air leakage does not exist inthe membrane 28. However, if the level of vacuum in the membrane 28 isbelow the predetermined range, it is determined that air leakage doesexist in the membrane 28.

When air leakage is detected in the membrane 28 through the aboveinspection (step S24), the membrane 28 is disassembled (step S19) inorder to be re-assembled (step S16). The leakage inspection test (I) andleakage inspection test (I I) (steps S18, S20 and S22) described aboveare then repeated on the re-assembled membrane 28.

Then, the retainer ring 22 is assembled to the base 14 once the membrane28 is assembled, thereby completing the assembling work of the polishinghead 10 (step S26).

Thereafter, a predetermined positive pressure is supplied to the tube 16c connected to the retainer ring 22. Then, the pressure 56 c supplyingthe positive pressure to the retainer ring 22 is shut-off and thepressure in the tube is measured in order to inspect for air leakage atthe retainer ring 22 (step S28). The method for inspecting for airleakage at the retainer ring 22 is substantially identical to themethods for inspecting for air leakage in the inner tube 30 and themembrane 28, except for the tube receiving the positive pressure, sodetailed description thereof will be omitted. The positive pressure issupplied only to the tube communicated with the retainer ring 22, andtubes communicated with the inner tube 30 and the membrane 29 areshut-off.

When air leakage is detected at the retainer ring 22 through the aboveinspection (step S30), the retainer ring 22 is disassembled (step S29)in order to be re-assembled (step S26). The leakage inspection test (I)(step S28) described above is then repeated on the re-assembled membrane28.

When the leakage inspection at the retainer ring (I) performed bysupplying the pressure is completed, the pressure in the retainer ring22 is vented to the exterior by opening venting valve 60 c connected, ina row, to first valve 58 c provided in pressure line 56 c.

Then, the vacuum is supplied to the retainer ring 22 in order to performleakage inspection at the retainer ring 22 (I I) (step S32).

If air leakage is detected at the retainer ring 22 through the aboveinspection (step S34), the retainer ring 22 is disassembled (step S29)in order to be re-assembled (step S26). The leakage inspection test (I)and leakage inspection test (I I) (steps S28, S30 and S32) describedabove are then repeated on the re-assembled retainer ring 22.

As described above, the polishing head is tested for air leakage at eachassembling step thereof, so that it is possible to assemble thepolishing head 10 without any air leakage.

Because the pressure and/or vacuum may be selectively supplied to themembrane 28, the inner tube 30 and the retainer ring 22, and because thepositive pressure and the level of vacuum are measured at each part towhich they are supplied, it is possible to test the polishing head 10for air leakage when it is completely assembled, or at various points ofassembly.

Another advantage of the present invention is that it is possible todetermine the pressure applied to each section of a wafer by thepolishing head during the polishing process. Therefore, it is possibleto apply uniform pressure to the entire wafer, thereby uniformlypolishing the wafer.

FIG. 6 shows a flow chart illustrating steps for determining thepressure applied to a wafer by the polishing head.

The tubes 16 a, 16 b and 16 c respectively communicated with themembrane 28, the inner tube 30 and the retainer ring 22 of the assembledpolishing head 10 are respectively coupled with the coupling lines 40 a,40 b and 40 c of the housing 42 in such a manner that the polishing head10 is supported by the housing 42 (step S50).

Then, the polishing head 10 is spaced apart by a predetermined distancefrom the seat sensor 84, i.e., a pad sensor, positioned opposite to thebottom of the polishing head 10 by moving the housing 42 up and downthrough the driving section 47. At this time, the distance between thepolishing head 10 and the seat sensor 84 is identical to the distancebetween the polishing head 10 and the polishing pad during the polishingprocess (step S52).

The positive pressure applied to each of the tubes 16 a, 16 b and 16 cof the polishing head 10 is identical to the positive pressure suppliedwhen the polishing process is carried out (step S54). Particularly, thepositive pressure is supplied from the main pressure regulator 52 viathe first connection line 56 and the pressure lines 56 a, 56 b and 56 c,and the pressure is adjusted to a predetermined pressure by means of thefirst valves 58 a, 58 b and 58 c connected to the pressure lines 56 a,56 b and 56 c and is transferred to each of the tubes 16 a, 16 b and 16c.

When the positive pressure is supplied to the tubes 16 a, 16 b and 16 ccommunicated with the membrane 28, the inner tube 30 and the retainerring 22 of the polishing head 10, the bottom of the membrane 28 isexpanded. In addition, the pressure is applied to the retainer ring 22and the inner tube 30 so that they make contact with the pad sensor 84.At this time, by detecting the pressure uniformity at each pad of thepad sensor 84, it is possible to inspect the polishing uniformity whenthe wafer is polished (step S56). Then, the pressure conditions arere-adjusted so as to achieve optimum polishing uniformity (step S58).

Therefore, according to the method for inspecting the polishing headaccording to the present invention, it is possible to assemble thepolishing head without the existence of air leakage, i.e., no loss ofpositive pressure or level of vacuum, in the tubes of the polishinghead. In addition, when the assembled polishing head is used, it ispossible to ensure uniform polishing of the wafer by measuring andregulating the pressure applied to the wafer.

While the present invention has been described in detail with referenceto the preferred embodiment thereof, it should be understood to thoseskilled in the art that various changes, substitutions and alterationsmay be made thereto without departing from the spirit and scope of theinvention as set forth in the appended claims.

1. A method for assembling a polishing head while inspecting for airleakage in the polishing head, comprising: i) assembling an inner tubeto a housing and a base; ii) supplying a first pressure through a firstpressure line to a first tube connected to the inner tube and inspectingfor air leakage by determining if there is any variation in the firstpressure in the first tube connected to the inner tube; iii) assemblinga membrane to the base once the inner tube is assembled; iv) supplying asecond pressure through a second pressure line to a second tubeconnected to the membrane and inspecting for air leakage by determiningif there is any variation in the second pressure in the second tubeconnected to the membrane; v) supplying a first level of vacuum througha first vacuum line to the second tube connected to the membrane andinspecting for air leakage by determining if there is any variation inthe level of vacuum in the second tube connected to the membrane; vi)assembling a retainer ring to the base once the membrane is assembled,thereby completing an assembling of the polishing head; vii) supplying athird pressure through a third pressure line to a third tube connectedto the retainer ring and inspecting for air leakage by determining ifthere is any variation in the third pressure in the third tube connectedto the retainer ring; and viii) supplying a second level of vacuumthrough a second vacuum line to the third tube connected to the retainerring and inspecting for air leakage by determining if there is anyvariation in the second level of vacuum in the third tube connected tothe retainer ring.
 2. The method as claimed in claim 1, wherein when airleakage occurs in ii), the assembled inner tube is disassembled and i)to viii) are sequentially repeated.
 3. The method as claimed in claim 1,wherein when air leakage occurs in iv) or v), the assembled membrane isdisassembled and iii) to viii) are sequentially repeated.
 4. The methodas claimed in claim 1, wherein when air leakage occurs in vii) or viii),the assembled retainer ring is disassembled and vi) to viii) aresequentially repeated.
 5. The method as claimed in claim 1, wherein, inii), iv) and vii), inspecting for air leakage is carried out by: a)supplying a predetermined pressure through a predetermined pressure lineinto a predetermined tube of the polishing head to be inspected whiletubes that are not subject to inspection are closed; b) closing thepredetermined pressure line, through which the predetermined pressure issupplied to the predetermined tube, once the pressure in thepredetermined tube reaches the predetermined pressure; c) determining ifthere is any variation in the pressure in the predetermined tube after apredetermined period of time after closing the predetermined pressureline; and d) determining whether air leakage occurs by measuring anypressure variation in the predetermined tube and comparing the pressurevariation with the predetermined pressure.
 6. The method as claimed inclaim 5 further comprising venting pressure from the predetermined tubesafter inspecting for air leakage in ii), iv) and vii).
 7. The method asclaimed in claim 1, wherein, in v) and viii), inspecting for air leakageis carried out by: a) supplying a predetermined level of vacuum througha predetermined vacuum line to a predetermined tube of the polishinghead to be inspected while tubes that are not subject to inspection areclosed; b) closing the predetermined vacuum line through which thepredetermined level of vacuum is supplied to the predetermined tube,when a level of vacuum in the predetermined tube reaches thepredetermined level of vacuum; c) determining if there is any variationin the level of vacuum in the predetermined tube after a predeterminedperiod of time after closing the predetermined vacuum line; and d)determining whether or not air leakage occurs by measuring any variationin the level of vacuum in the predetermined tube and comparing thevariation in the level of vacuum with the predetermined level of vacuum.8. The method as claimed in claim 1, further comprising ascertaininguniformity of polishing by applying a pressure to each of the tubes ofthe polishing head after the polishing head is assembled.
 9. The methodas claimed in claim 8, wherein ascertaining the uniformity of polishingcomprises: a) adjusting a first distance between the assembled polishinghead and a pad sensor positioned opposite to a bottom of the polishinghead to be identical with a second distance between the polishing headand a polishing pad in a course of a polishing process; b) applying apressure identical to the pressure applied during the polishing processto each of the tubes of the polishing head; and c) detecting thepressure applied to each part of the pad sensor when the bottom of thepolishing head makes contact with the pad sensor by the pressure appliedto the polishing head.